The present invention relates generally to machines and methods for shearing pile-type textile fabrics and, more particularly, to the control of such machines for producing reliably repeatable shearing results from one shearing operation to another.
The basic structure and operation of textile fabric shearing machines is well-known and has not changed significantly in recent years. Basically, textile shearing machines have a machine frame on which a shear cylinder, typically equipped with a plurality of helically or spirally extending shear blades projecting outwardly at circumferential spacings from the cylinder periphery, is mounted for driven rotation. A traveling length of a pile or plush textile fabric is trained through the machine about a series of guide rolls and is presented to the rotary periphery of the shear cylinder for cutting of the pile surface of the fabric by passing the fabric over an elongate cloth or fabric rest which extends in a stationery disposition on the machine frame alongside the periphery of the cylinder. An elongate ledger blade is similarly mounted on the frame alongside the cylinder periphery adjacent the fabric rest. The ledger blade has an arcuate surface conforming to the periphery of the cylinder, which surface terminates at a sharpened edge extending in shear cutting relation along the periphery of the cylinder at a close spacing to the fabric rest. In operation, as a pile or plush fabric is passed over the fabric rest, the fabric rests acts to cause the plush or pile surface of the fabric to extend into the nip area between the cutting edge of the ledger blade and the peripheral cutting blades of the shear cylinder so as to be severed to a desired degree determined by the relative spacing and dispositions of the cylinder, ledger blade, and fabric rest.
It is known to be important that the fabric deflecting surface or edge of the cloth rest and cutting edge of the ledger blade should be precisely linear and parallel to one another and also to the axis of the shear cylinder in order to insure uniform shearing of the plush or pile surface of the fabric so as to avoid production of second quality fabric. However, even with these operating components of the shearing machine in properly aligned disposition relative to one another, it is still difficult to repeatably produce comparable shearing results from one machine to another and from one roll of fabric to another, because other variables may affect the shearing operation, e.g., the rotational speed of the shearing cylinder, the traveling speed of the fabric, etc.